Smart phones, tablet computers and other mobile terminals, with their powerful functions and convenience, play an important role in people's work and life. It can be seen from current development trends of mobile terminals that smart terminals have increasingly larger display screens, more powerful functions, and a higher processing speed, and support multiple universal serial bus (USB) interfaces. These developments often cause the mobile terminals to consume more power. In order to extend standby time of mobile terminals, a method of increasing battery capacity is often adopted. However, due to an increase in the battery capacity, in order to ensure that the charging time is not changed, it is necessary to increase a charging current, which inevitably puts forward a higher requirement on a charging system.
At present, low-energy mobile phones or tablet computers are charged mainly through a single interface. Electrical current, carried by a USB interface, is typically designed according to a USB interface industry standard, and a nominal current (i.e., charging current) is often required to be 500 mA. The typical charging ability, of a standard USB interface, is far from meeting the requirements for large battery capacity and a same or shorter charging time of the ever-growing mobile terminals. More and more mobile terminals require charging currents much higher than the electrical current provided by a standard USB. Therefore, a large-current charging device, and stable power supply, for smart terminals is desirable.
There are generally three charging methods for mobile terminals. The first method of charging is through a USB interface, which is typically only suitable for small-current charging, and charging time is prolonged if battery capacity of a mobile terminal is large. The second charging method employs a DC charging stand. DC charging stands are typically non-standard, and need a special DC charging interface. Use of USB interfaces, with non-standard DC charging interfaces, leads to an increase in a number of special accessories of the required for a mobile terminal, thereby greatly increasing the cost, and resulting in poor user experience. The third charging method is hybrid charging using a USB interface for small-current charging, and using a special DC charging interface for large-current charging. Hybrid charging typically has high requirements for control over values of currents, combination of large and small currents, and compatibility of the USB interface, and typically has a high cost.
Therefore, the prior art remains to be improved and enhanced.